1. Technical Field
The present disclosure relates to fluid lock ports for use in flushing/locking procedures and, more particularly, to positive displacement fluid lock ports for use in combination with an indwelling catheter and a syringe during a flushing/locking procedure.
2. Background of Related Art
Numerous techniques are employed for the administration of “medical liquids” (e.g. liquid medication and flush/lock solutions) to a patient. In particular, where repeated medication infusions are required, medical liquids are often administered via the use of a vascular access catheter that is fluidly interconnected or interconnectable to one or more medical liquid sources via an associated tubing line set. Typically, the catheter is inserted into the vein of a patient and left there for multiple intravenous (IV) infusions during an extended course of medication therapy.
In conjunction with the repeated connection/disconnection of a vascular catheter and liquid medication source and tubing line set, it is usual practice to purge the vascular catheter with a flush solution (e.g. a saline solution) prior to and at the completion of a given liquid medication infusion. Pre-infusion flushing verifies that the vascular catheter is primed and clear of obstructions. Post infusion flushing/locking not only flushes through any remaining liquid medication to achieve the desired therapeutic effect, but also reduces any chance that the vascular catheter may become blocked in-between infusions, e.g. by a blood clot that may otherwise form in the vascular catheter.
A number of approaches are currently utilized for the noted flushing/locking procedures. Such techniques generally entail the usage of flush/lock solutions packaged in large volume, multi-dose reservoirs (e.g. about 250 ml. or more) or pre-filled unit dose syringes (e.g. having volumes of 2, 3, 5 or 10 ml.).
Flush/Lock procedures also require that care be taken to prevent blood reflux into the catheter. Reflux in I.V. therapy is the term commonly used to describe the fluid that is drawn back into the catheter after a flush/lock procedure. The concern is that the reflux fluid contains blood or solution that could cause the catheter to occlude. To ensure that reflux does not occur, flush/lock procedures suggest two techniques: 1) at the end of the flush/lock solution delivery, the user maintains pressure on the syringe plunger while clamping the I.V. line; or 2) while delivering the last 0.5 ml of flush/lock solution, disconnect the syringe from the I.V. port or clamp the I.V. line. Either technique maintains positive pressure on the fluid in the VAD to prevent reflux of fluid and blood.
For example, for hemodialysis procedures, catheters are commonly used for aspiration of blood for dialysis treatment and rapid return of the blood to circulation after treatment. In certain instances, a large bore venous line catheter may be required for the hemodialysis procedure. Catheters used for hemodialysis usually include two relatively large diameter lumens (usually molded as one catheter) for aspiration and rapid return of blood required during the hemodialysis procedure.
Catheter connections, such as, for example, connections of catheters to dialysis machine tubing, to IV line tubing, to infusion ports are most often made utilizing the medical industry's standardized Luer taper fittings. These fittings, which may either be male couplings or female couplings, include a tapered end of standardized dimensions. Coupling is made by the press-fit of mating parts. A threaded lock-fit or other type of securing mechanism is commonly utilized to ensure the integrity of the pressure fit of the Luer fittings.
A drawback of catheters is that, over time, a catheter can become occluded by a thrombus. In order to prevent clotting of catheters in blood vessels between uses such as, for example, between dialysis treatments when the catheter is essentially nonfunctioning and dwells inside a “central” vein (i.e. superior vena cava, inferior vena cava, iliac, etc), the lumens of the catheter are often filled with a lock solution that comprises a concentrated solution of the commonly used anticoagulant, heparin (up to 10,000 units of heparin per catheter lumen).
Following filling of the catheter with the lock solution, disconnection of the filling syringe from the catheter may result in some amount of drawback or reflux, i.e., wherein the catheter draws in some body fluid (e.g., blood), which may result in clotting thereof or the like.
It is desirable to have syringe assemblies and the like that are designed to minimize or reduce the incidents of reflux without depending entirely on user techniques.
Accordingly, there is a need for a device which helps to reduce or eliminate the incidents of reflux and which is independent of user technique.